Analysis Measures Of Stick-Slip Induce Launch Click Noise

With the development of science technology and the increasing living standards of people,users are increasingly demanding the quality of automobiles such as safety,riding comfort,NVH(Noise,Vibration and Harshness)and durability.In automotive power train,Stick-slip vibrations and noise are often generated due to relative rotational friction between components,and such friction-induced stick-slip vibrations can seriously affect NVH,safety,etc.such as wiper noise,brake flutter,etc.Therefore,it is important to explore the stick-slip friction characteristics of the power train for the NVH performance control.At the same time,it has certain reference for the stick-slip friction control of other similar structures and the stick-slip risk avoidance in advance.In this paper,for the engineering practice of the abnormal ‘click' sound of the wheel end of a car model and the abnormal ‘click' sound of the transmission output end of a SUV model,the subjective and objective evaluation analysis method and the structural analysis method are applied to analyze the abnormal “click” sound source and provide different control measures to suppress the problem of abnormal ‘click' sound stick-slip friction and noise.The research content and problems to be solved in this paper are mainly reflected in the following aspects:1 Firstly,for the abnormal ‘click' sound of the wheel end of a car model under the starting condition,the abnormal sound source is found through subjective and objective evaluation.At the same time,the method of changing the locking torque is used to further identify the abnormal ‘click' sound source.Finally,the abnormal ‘click'sound source is locked at the contact area between the wheel hub bearing and the transmission half shaft assembly contact surface.At the same time,the structural characteristics and assembly characteristics of different types of wheel hub bearings are analyzed.The first-generation wheel hub bearing assembly structure used in this model has the possibility of stick-slip friction.2 Through the vehicle and transmission system parameters,the AMEsim wheel end stick-slip abnormal ‘click' sound simulation model is established,such as clutch,transmission,differential,shaft,wheel and Karnopp friction model.The engine output torque,speed and other signals measured by the actual vehicle under the starting conditions are input into the model as excitation,and the shifting process and shift position of the actual vehicle test are used as the clutch and synchronizer control signalsin the simulation model.The simulation results show that the friction torque in the Karnopp friction model suddenly changes during the starting process,that is,the static friction torque(200N · m)instantaneously changes to the dynamic friction torque(145N·m),indicating that there is stick-slip characteristics during the starting process.In addition,the effects of engine output torque,friction coefficient and Stribeck constant on stick-slip friction are also simulated.(3)According to the assembly structure between the driving half shaft and the hub bearing and the AMEsim stick-slip simulation analysis conclusions,a variety of engineering control measures are proposed and the performance differences of different control measures are compared.At the same time,considering the structural characteristics of the reference wheel hub bearing on the market,considering the control performance,durability,cost and other factors,the method of adding the friction reducing washer with special anti-friction coating between the driving half shaft and the wheel hub bearing successfully solved starting;click' abnormal noise.(4)Based on the analysis method and conclusion of the analysis of the abnormal‘click' sound of the wheel end of the car model,it is successfully applied to the analysis and control of the starting noise of the transmission output of another SUV model.Since the working condition of the output end of the transmission is better than that of the wheel end and according to the actual assembly structure,the more economical and practical anti-friction washer control measures with oil storage micro-slots are successfully applied.In summary,this paper takes the control of the starting noise of two models as the carrier,comprehensively and systematically analyze the problem of stick-slip vibration and noise between the contact interface between a half shaft and a wheel hub bearing of a car and the transmission output shaft and coupling of a SUV model.The problem of stick-slip noise between the contact interfaces of the device has been analyzed and improved to meet various technical indicators,which not only meets the current development needs,but also accumulates some experience for the development of subsequent models.